Carswell has announced that he will resign as an MP immediately and contest the by-election for UKIP.
Commentators are noting that Carswell has a huge grassroots following and personal vote, and may be able to hold his seat in the by-election to give UKIP its first ever victory in a Westminster constituency.
Having filmed with Carswell in Clacton and seen his massive personal, rather than Tory, following, Clacton may go UKIP in this by election
— Allegra Stratton (@BBCAllegra) August 28, 2014
Carswell becomes UKIP's second ever MP, following Bob Spink who briefly called himself a UKIP MP after leaving the Conservatives in 2008 before turning into an independent. Spink represented the Castle Point constituency, and tried to defend his seat in 2010 for his own Independent Save Our Green Belt Party, coming second with 27% of the vote (full result).